// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#ifndef STORAGE_LEVELDB_TABLE_BLOCK_BUILDER_H_
#define STORAGE_LEVELDB_TABLE_BLOCK_BUILDER_H_

#include <cstdint>
#include <vector>

#include "leveldb/slice.h"

namespace leveldb {

    struct Options;

    class BlockBuilder {
    public:
        explicit BlockBuilder(const Options *options);

        BlockBuilder(const BlockBuilder &) = delete;

        BlockBuilder &operator=(const BlockBuilder &) = delete;

        // Reset the contents as if the BlockBuilder was just constructed.
        void Reset();

        // REQUIRES: Finish() has not been called since the last call to Reset().
        // REQUIRES: key is larger than any previously added key
        void Add(const Slice &key, const Slice &value);

        // Finish building the block and return a slice that refers to the
        // block contents.  The returned slice will remain valid for the
        // lifetime of this builder or until Reset() is called.
        Slice Finish();

        // Returns an estimate of the current (uncompressed) size of the block
        // we are building.
        size_t CurrentSizeEstimate() const;

        // Return true iff no entries have been added since the last Reset()
        bool empty() const { return buffer_.empty(); }

    private:
        const Options *options_;
        std::string buffer_;              // Destination buffer
        std::vector<uint32_t> restarts_;  // Restart points
        int counter_;                     // Number of entries emitted since restart
        bool finished_;                   // Has Finish() been called?
        std::string last_key_;
    };

}  // namespace leveldb

#endif  // STORAGE_LEVELDB_TABLE_BLOCK_BUILDER_H_
